1. Field of the Invention
This invention relates, in general, to combined cycle power plants of the type that include at least one combustion-type turbine and at least one steam-type turbine. More specifically, this invention relates to an improved system for recovering waste heat from a combustion turbine in such a combined cycle power plant.
2. Description of the Prior Art
It is well known in the field of power generation to provide one or more steam turbines in a plant with one or more combustion-type turbines and to use the waste heat contained in the exhaust of the combustion turbines to generate motive steam for the steam turbines. Plants such as these are typically referred to as "combined cycle power plants."
In a combined cycle-type power plant, spent motive steam from the steam-type turbine is condensed into a liquid condensate in a condenser. The condensate is then pumped through a deaerator and from the deaerator into one or more heat exchangers that transfer heat from the exhaust gases of the combustion-type turbine to the condensate. In the heat exchangers, the waste heat from the combustion turbine exhaust is recovered to heat the condensate back into steam, which is then redirected to the steam-type turbine. Such a system is disclosed in U.S. Pat. No. 4,961,311 to Pavel et al.
Unfortunately, some waste heat from the turbine exhaust remains unrecovered in even the most efficient conventional combined cycle power plants, and is released to the environment. It is generally recognized that any improvements that permit recovery of some of the presently unrecoverable waste heat to increase plant efficiency would be desirable.